Some power conversion systems, for example, dual interleaved boost power factor converter (PFC) systems, make use of magnetically coupled inductors or coils wound around a magnetic core. For instance, referring to FIG. 1A, a magnetic core 150 of a boost converter includes a first set of inductor coils 152 and a second set of inductor coils 154. Inductor coils 152 are disposed around a first leg 156 of a core 158, and inductor coils 154 are disposed around a second leg 160 of the core. Energy storage in boost converter 150 is localized in a center leg 162 including a gap 164. The magnetic (H) field in gap 164 is oriented perpendicular to the wide axis of inductor coils 152 and 154. Boost converters including magnetic core 150 are generally suitable for a power throughput of about a few hundred Watts. However, attempts to scale up such boost converters may face efficiency limitations in some systems, for instance due to geometry constraints and/or eddy current losses when the power rating is increased beyond the 1 kW range. In some examples, the power conversion systems are used in professional sound systems.
Some power conversion systems make use of one primary winding and multiple secondary windings, with one of the secondary windings being used to provide “housekeeping” power to control circuitry, such that a separate power conversion component is not needed to power the control circuitry. In situations in which the control circuitry requires power during standby periods, the production of housekeeping power may be inefficient, for example, due to losses in the switching components of the system driven by the primary windings. This inefficiency negates some of the advantages of sharing the primary windings for multiple sets of secondary windings during normal operation.
Referring to FIG. 1B, an example of a dual interleaved boost converter circuit 100 includes inductors L1 112 and L2 114, which are magnetically coupled across a common core 102. The degree of coupling between the inductors is controlled by the width of the gap separating the windings of the two inductors. The maximum flux ripple in the core of the dual interleaved boost converter circuit 100 is roughly half that of a single boost circuit, and the AC ripple on the dual interleaved boost circuit is also reduced. Two switches Q1 122 and Q2 124 (e.g., metal-oxide-semiconductor field effect transistors (MOSFETs)) are duty cycle controlled and typically run 180° out of phase, although in some cases 90° operation may be preferable. A circuit having sufficiently coupled inductors exhibits little to no ripple current.